The proposed studies are part of a long range program to understand the organization and function of adrenal chromaffin vesicles and how they interact with the plasma membrane during secretion. Dopamine-beta-hydroxylase, the enzyme which forms noradrenaline from dopamine is present in the chromaffin vesicle in both a soluble form and as a membrane-bound protein. We, as well as others, have been interested in characterizing these two forms of the enzyme to possibly help explain why some proteins are tightly associated with membranes. The soluble form of the enzyme has been purified to homogeneity by several laboratories including ours, but only in the past year have we been able to purify the membrane enzyme. We now propose to characterize each of the enzymes with respect to their molecular weight, subunit organization, amino acid and carbohydrate composition, fingerprint of tryptic digests, lipid and detergent binding and immunospecificity.